"This thing is so damned cool," John remarked, watching the water in the glass kettle roiling furiously inside. The head of steam built up, clicking the power off. John picked it up and poured the water into the good teapot.
"The old one was boring," Sherlock replied absently, his gaze focused on his laptop screen. "I wanted particularly to choose an impressive one."
After a moment, John said, "Oh. So on the last day of Moriarty's trial, you got that kettle for the same reason that you cleaned up the flat and set out all your best lab equipment." John smirked as he sipped at his tea. "Well, I hope he was duly awed by the kettle that looks like a miniature nuclear power plant cooling pool."
Sherlock snorted. "No. He never saw it in operation. After the verdict, Moriarty was escorted out of the courtroom and to his waiting car, and began the eighteen minute trip to the flat. But I calculated it would take seventeen minutes for the judge to dismiss the court and for you to get outside Old Bailey to notify me. I turned it on then."
Sherlock smiled at the memory. "One minute and thirty-eight seconds after he pulled up at the kerb, I was able to greet him with quintessential British hospitality: 'Kettle's just boiled.'"